Photographic paper.



A. C. MCCLOSKEY.

PHOTOGRAPHIC PAPER.

APPLICATION man MAR. l2. |915.

Patented Jan. 30, 1917.

W/T/VESS.'

FRED c. MecEosKEY, oEEHILADELPHIA, PENNSYLVANIA, AssIGNon` 'ro Pnocnss PAPER. MANUFACTURING CQMPANY, AfconronA'rIoN or' DELAWARE.

PHOTOGRAPHIC PAPER.

Specication of Letters Patent. Patented an. 3U, 1917.

Application led August 12, 1915. Serial Ito. 45,226.

To all whom it may concern.'

Be it knownv that L ALFRED C. MCCLos- KEY, a citizen of the United States, residing at the city of Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented a certain new and useful Pho'- tographic Paper, of which the following is a s ecication.

here are photographic papers on vthe market and .finishing processes in use by which prints in vappropriately colored lines on a white or substantially white back-v ground can be produced from tracings or the like by exposure either to the suns rays or tol artlcial light. The prints, like'the tracings, have dark images on White or substantially white grounds and no negative .is used. Such processes are characterized bythe` use' of `a light sensitive coating containing, perhaps, among other things an organic substance as gum, and ferrie salt or salts 'which upon exposure to lightare Aconverted to the ferrous state or condition, andthat potassium ferrocyanid is used as a developer, the

use of staining solutions being optional, and that sulfuric acid is the clearing solution. In reference to such papers it has beeny said' that they are provided with such sensitized coatings as are normally insoluble in the clearing solutions, but are rendered soluble by exposure, butwhether this beabsolutely accurate ornot is perhaps not material since the above descriptionsufiiciently identifies theiclass' of photographic papers upon which the present invention is an improvement. However, in ythe finishing process or operation, such known papermust be wet only on the front or face,l 'otherwise the back ofthe laper will be stained oi'discolored bythe solotions: used or i by `impl'irities therein, and these stains and discolorations are not only unsightly n'themselvesbut also frequently show through from the front.' v

' It is the principalpbject ofthe present invention to provide improved' photographic paper of the .general kind-referred 'to and which can be immersed in or wet upon both v sides with inishing solutions without danger ofdiscoloratio'n or stains on the back, whereby theprocess of finishing the prints is faclitated and the production of prints with clean backs is insured. i

lnamuch as my invention is an improvement in an existing art, I believe that it can be best explained by describing it in connec-y tion with a known process and means. For this lpurpose and not as alimltatlon or restriction of the application-or use of the inscription: Pellet paper is coated on one -face'with a coating containing gum arabic, tartaric acid and lferrie chlorid. The developermay be potassium ferrocyanid and the clearing solution may be sulfuric acid. Staining. solutions may, of course, be employed when-it is desired to produce, .for example,v black instead of blue lines on a white ground from a tracing or the like inwillich. the lines are' black and the ground is W ite. v l ln Pizzighellis modilication of the Pellet process the coating that is applied to one Side of thel paper contains gum arabic, ammonium ferriecitrate, and ferric chlorid. The finishing vsolutions are the same.

My photographic paper differs from and is an improvement upon FPell'ets or like orequivalent paper in that, while its face is generally orv substantially the `same as those 4known papers, its back-is provided with a coating 4soluble in or rendered removable by the clearing solution,and inert in or impermeable to'or not permanently affected by not. onlythe developingsolution but also the staining and fixing solutions where the two latter are employed for producing-.black or dark instead of blue or like lines. Photographic paper of my invention is, las heretofore, provided upon the face with a ferrie light sensitive coating, but it is vadditionally provided upon the back with a coating soluble in or removable by the clearing solution, whereby the paper, after printing, can be immersed in all the solutions used, and will resent, when finished,

a clean back free rom discolorations or stains.

In the accompanying drawings which are diagrammatic representations. Figure 1 is a front view.v Fig. 2, is a transverse sectional view of paper embodying features of, the inventionpand Fig. 3, is a sectional view, embodying a modification.

In the drawings 2, is a light sensitive coating containing, among other things, ferrie salts and this coating-may be substantially the coating of the type above described as Pellets and Pizzighellis. The coating lis characterized asbeing vferrous and it may be produced by making it originallythe same as the coating 2, that is, ferrie, and exposing- Pellet and lfizzighelli;y After the face ofthis paper has been exposed to light under a tracing, or the like, it is developed w1th potassium ferrocyanid, stained or not as may be required with appropriate staining solutions'that are well known and cleared with a sulfuric acid-solution. Of 'course in the processA the print is washed as usual with water. The finished print will havea white back, a white ground andan image m dark lines.

One way of making paper embodying features of my invention is to provide both sides of the paper with a ferrie light sensitive coating and to primarily expose one side to convert the ferrie coating to a ferrous non-light sensitive coating, thus producing the back. After such paper is printed upon the ferric light sensitized side or face, the part of the coating on the face which has been exposed is therefore ferrous and the same as the coating on the back. In consequence the coating on; the back and the part of the coating on the face which has been exposed will respond and behave alike in the finishing solutions-potassium ferrocyanid, the developer, sulfuric acid the clearingsolution, andstaining solutions if employed-so that the paper can be immersed therein or wet therewith without danger of staining or -discoloring the back, because anystains or discolorations produced on the b ack by reason of the character of the solutions used or of impurities therein are removed by the action of the clearing solution.

Another way of making photographic paper embodying features of the invention is to provide the back of the paper with a coating initially ferrous and removable by or soluble in the clearing solution. This coating is not light sensitive and is not primarily exposed, but performs the function of preventing stains and discolorations on the back because it protects vthe same and is only removed by the clearing solution.

The word paper is used herein in its ordinary sense and so as to include linen, tracing-cloth, or any equivalent material, and the word tracings includes plates,vi1ms, transparencies and the like.

From the foregoing description it is obvious that changes may be made in details by substituting equivalents in the applicamaracas tion of theI invention to diierent known papers and printing processes, so that the invention is not limited in those respects nor otherwise than as the claims may require.

What I claim is:

1. Photographic paper for producing prints having dark images on light grounds from tracings and the like, provided upon the face with a light sensitive coating containing ferric salts and provided upon the back with a coating containing ferrous salts and removable by the clearing solution,

whereby the paper after printing can be immersed in or wet on both sides with the appropriate solutions tending to stain it and will, when finished, present a clean back free from discolorations or stains.

2. Photographic paper for producing prints having dark images on light grounds from tracings and the like, provided upon each face with a coating of. which the coating on the face contains ferrie Salts and of which the coating on the back has been primarily exposed to reduce ferric salts to ferrous salts, whereby the coating on the back comes off in the clearing solution to provide a clean stainless back.

3. Photographic paper for producing prints from tracings and the like provided on its back .with a coating which does not produce images and which is removable by the clearing',` solution, substantially as described.

4. Photographic paper for producing prints having dark images on light grounds from tracings and the like. provided upon one face with a light sensitive coating and upon the other face with a non-printing protective coating having the same behavior in respect to the finishing solutions as have the portions of the light sensitive coating after they have been exposed in printing, substantially as described.

5. Photographic paper having on the back thereof a non-printing coating impermeable to stains from the finishing solutions and removable by the clearing solution.

6. A photographic paper having on the face a sensitizing coating adapted to be finished by solutions which produce stains, and having on the back a protective coating entirely removable by the clearing solution.

7. Photographic paper for producing light ground dark line prints directly from tracings and having on the face a sensitizing coating and requiring protection for the back, and having on the back a non-developing protective coating of substantially the same characteristics as are imparted to the face coat by light exposure and entirely removable by the clearing solution, substantially as described.

8. Photographic paper for producing from tracings and the like prints having arman dark lines or marks Where' the tracing has back with a non-developing coating the same dark lines or marks and having a light as that part of the coating on the face which ground Where the tracing has a light ground after printing is inert in `the developing l@ and adapted after immersion in the fnishsolutions and removable by the clearing ing solutions to present on the back a paper solution. surface free from stains and images.

9. A photographic paper covered on the ALFRED C. MCCLOSKEY. 

